1. Technical Field of the Invention
The present invention pertains in general to cellular telephones and pagers, and more particularly, to a method for selecting a radio signal to be received by a device possessing cellular telephone and pager capabilities and sharing a common receiver.
2. Description of Related Art
Reduced cost and wide spread acceptance of both cellular telephone and pager services has resulted in consumers desiring to subscribe to both cellular telephone and pager services. In the past, consumers had to purchase and carry a separate cellular telephone and paging device. To meet this market segment, manufacturers of cellular telephones and pagers have aggregated the two devices into a single unit. Such an aggregated unit is more convenient to carry than two separate devices. While the aggregated device may share some components such as a housing, a battery, a tone generator (ringer/beeper) and possibly an alphanumeric display between the cellular telephone and the pager, the aggregated unit is essentially two distinct devices capable of independent and simultaneous operation.
Due to the commonality of components between the pager and the cellular telephone, certain further components can also be shared between the devices thereby reducing duplication of components, reducing cost and furthering miniaturization. In particular, a significant savings can be realized by sharing the radio receiver. Although the radio frequencies for cellular telephones and pagers are different, it is well known in the industry to design a receiver capable of operation in different frequency bands. The drawback to sharing components, however, is that only one device can utilize these components at any given time and simultaneous operation of both devices is not possible.
It is well known in the industry that cellular telephones and pagers operate most of the time in sleep mode. In the sleep mode, the device, whether it be a cellular telephone or a pager, powers down all components except the receiver in an effort to conserve scarce battery power. Furthermore, the receivers themselves power down and activate or "awaken" only during allocated time periods during which they monitor a paging channel for notification of incoming traffic. The timing and frequency of the paging periods is well known and is specified by the particular protocol of the communication system (e.g., GSM, AMPS, POCSAG, etc.) and the identity of the mobile device.
Since current aggregations of cellular telephone/pager devices sharing a single receiver can operate only as a cellular telephone or pager at any given time, it would be advantageous to provide a method for sharing the receiver such that, in non-overlapping situations, the receiver monitors the cellular telephone paging channel during the cellular telephone paging time periods and monitors the pager paging channel during the pager paging time periods thereby providing simultaneous cellular telephone and pager service. There is also a need for a method of prioritizing the type of service that will be provided during time periods when the cellular telephone paging time period and pager paging time period overlap.